SPECTRUM™

Type: Printed iridescent security feature — optically variable ink applied by screen or offset printing to paper or polymer banknote substrate

Overview

Spectrum™ is a De La Rue proprietary iridescent print security feature, classified within the broader family of optically variable ink (OVI) effects. It belongs to a category of printed security features that use specialised interference pigments — typically mica-based flakes coated with thin metallic or oxide films — to produce angle-dependent colour effects that cannot be reproduced by photocopying, scanning, or standard commercial printing. The name reflects the feature's characteristic behaviour: as the note is tilted through a range of viewing angles, the printed element shifts across a visible colour range, making its response both visually striking and immediately recognisable.

Technology & Effects

The optical effect of Spectrum™ derives from thin-film interference within the layered pigment structure. When light strikes the pigment at different angles, constructive and destructive interference of reflected wavelengths produces a perceived colour shift — the exact colours and transition range being determined by the film thickness and material composition, which are controlled during ink manufacture. At straight-on viewing angles the element is visible as a metallic or pearlescent design element integrated into the note's printed design; tilting the note reveals the characteristic colour sweep that gives the feature its authentication value.

The feature is applied by screen or offset printing, allowing it to be registered precisely to specific areas of the banknote design — denomination numerals, national motifs, background patterns — without requiring a separate foil application stage. This makes it well-suited to designs where security features need to be woven into the thematic content of the note rather than appearing as discrete applied elements.

Form Factors & Application

Spectrum™ is a printed-on feature applied directly during the banknote printing process. It is compatible with both paper and polymer substrates and can be applied as a patch, stripe, or design-integrated element. Because it is print-applied rather than foil-applied or substrate-embedded, it adds no additional thickness to the note and can be overprinted or combined with other printed security features within the same design layer.

Security Levels

Spectrum™ operates as a Level 1 (public) authentication feature. The colour-shifting response is visible under normal ambient lighting without any tools or special illumination, and the tilt-activated effect is unambiguous and easy to communicate in public education campaigns. The controlled ink chemistry and print geometry required to reproduce a convincing angular response provides a meaningful barrier against casual counterfeiting, particularly for offset-reproduced counterfeits that lack the necessary pigment formulation.

Name

SPECTRUM™

Category

Security Feature

Effect Types

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Company

De La Rue
Company Website

Product Page

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Linked Features

1 security feature